Q. I need some sort of cover crop or “green manure” planting that would improve the quality of the soil where I’ve pulled out some early vegetable plants. What would be my best choice?
A. For a fast-growing, soil-replenishing planting at this time in the year, your best choice is probably buckwheat. Seed should be available at some garden centres and farm supply stores.
Buckwheat can be seeded now. It is a summer soil-building cover crop that grows very fast and densely, smothering weeds. Chop it down and dig it under as it begins blooming. Depending on the weather, the plants may bloom around six weeks after seeding.
The succulent growth breaks down quickly when turned under. As it decomposes, buckwheat adds organic matter to the soil and improves its texture.
Q. Why are my prized tuberous begonia plants developing powdery mildew on the foliage? What can I do? Will the tubers be all right?
A . Powdery mildew is common on tuberous begonias. Weather conditions and/or stress of some sort are the usual causes.
Warm days, cool nights, and humidity foster powdery mildew. Drought-stressed plants become very susceptible to infections. Over my years of growing tuberous begonias in hanging baskets, I’ve noticed powdery mildew on some of the leaves after I’ve not been watering as carefully as usual.
Remove some of the most severely affected leaves. Rinsing the leaves off several times a week, at mid-day, will help to wash off spores and minimize infections. Don’t do this later in the day. The leaves need to go dry into the night.
In the fall, carefully clean away all top growth once it has died back, and the stems fall away at a light touch. Brush excess soil from the tubers, dust them lightly with sulphur powder and store in a cool but frost-free location. I cover mine with vermiculite. They should be fine.
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